Early permian strata in two displaced terranes of the McCloud belt contain a small biconic gastropod of distinctive appearance, Vesperispira humboldtiana new genus and species. This trochiform gastropod has a strongly oblique aperture with interrupted peristome, a small sinus on the peripheral margin of the shell, and lamellose shell. This gastropod is an easily recognized biogeographic indicator of the McCloud province biota, because of its lamellose ornamentation. Occurrence of this gastropod in strata of the Pine Forest Range of northwestern Nevada provides additional evidence for including rock units of the Black Rock terrane within the McCloud Belt, a grouping of...

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